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Rutherford alpha particle scattering

  1. Mar 25, 2007 #1
    1. The problem statement, all variables and given/known data

    A parallel beam of alpha particles with fixed kinetic energy is normally incident on a piece of gold foil.
    a) if 100 alpha particles per minute are detected at 20 degrees, how many will be counted at 40, 60, 80 and 100 degrees?
    b) If the kinetic energy of the incident alpha partilces is doubled, how many scattered alpha particles will be observed at 20 degrees.
    The density of the gold foil is given to be 19.3 g/cm^3

    2. Relevant equations / Attempt at solution

    N = k/[sin(theta/2)^4] ... My question is in relation to the relevant equations. I attempted to use this equation (substituting values given for scattering at 20 degrees to find 'k') for part a), though i am fairly sure there is more to it than this, could someone please point me in the right direction with regard to other equations relevant to this problem? I'm afraid i am lacking a text and have had no luck with google!

    Thank you for your time.
  2. jcsd
  3. Mar 25, 2007 #2
    a.) 40 - 50
    60 - 25
    80 - 10
    100 - 5

    b.) 2x 200 2He4
  4. Mar 25, 2007 #3
    Thank you for the response .ultimate, i was wondering if you could tell me how you came to get those answers? Perhaps you could tell me what equations were used, or how you came to that conclusion?

    Thank you
  5. Mar 25, 2007 #4


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    Homework Helper

    I don't think he used 'equations'. He made them up. It sounds like you are doing exactly the right thing for part a). Do b) in more or less the same way - but now you'll need to know the dependence of k on the kinetic energy. Here's a reference:

  6. Mar 25, 2007 #5
    Thanks Dick :cool:
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